Scientists pinpoint deadly brain tumor’s origin

A team of researchers have discovered the type of cell that is at the origin of brain tumors known as oligodendrogliomas, which are a type of glioma -- a category that defines the most common type of malignant brain tumour.

Investigators found that the tumour originates in and spreads through cells known as glial progenitor cells -- cells that are often referred to as “daughter” cells of stem cells. The work comes at a time when many researchers are actively investigating the role that stem cells, which have gone awry, play in causing cancer. For scientists trying to create new ways to treat brain tumours, knowing whether stem cells or progenitor cells are part of the process is crucial.

“In many ways progenitor cells are controlled by completely different signalling pathways than true stem cells,” said Steven Goldman, a University of Rochester neurologist who was part of the study team. “Knowing which type of cell is involved gives us a clear look at what drug approaches might be useful to try to stop these tumours. Comparing normal progenitor cells to progenitors that give rise to tumors gives us a roadmap to follow as we try to develop new treatments.” The study focuses on oligodendrogliomas, a type of tumour that presents with symptoms much like other brain tumours -- headaches, seizures, and cognitive changes. The tumours are treated with a combination of surgery, radiation, and chemotherapy.

Oligodendrogliomas at first are less deadly and invasive than most other gliomas. Unfortunately, treatments like surgery typically slow or stop the tumour initially, but it usually returns, often in a much more aggressive form than it was to begin with. The majority of patients with oligodendrogliomas ultimately die from the disease.

In order to identify better treatments for this tumour, researchers need to know what cell type in the brain gives rise to it. Despite abundant clinical experience with this type of cancer, no one had ever defined oligodendroglioma’s cell of origin. To answer this question, the team used a common brain tumour drug, temozolomide, to test several types of cells from both human and mouse tumours. They found that the drug was effective against oligodendroglioma cells and normal glial progenitor cells, and much less effective against either brain stem cells or other brain tumours called astrocytomas.

The work is the latest in a string of findings that progenitor cells are the origin for some brain tumours. The study has been published in the issue of the journal Cancer Cell.